As efforts continue to clean the oil that gushed from the blown-out well in the Gulf of Mexico, a team of scientists has found that nature's microbial helpers are hard at work too — and doing a better job than researchers had expected.
Data collected in May and June showed populations of carbon-eating bacteria were increasing in parts of a plume of oil drifting in deep water in the gulf, said lead author Terry Hazen, head of Lawrence Berkeley National Laboratory's ecology department.
"Within the last few weeks we've gone back and can find bacteria … but do not see detectable oil," Hazen said. The most likely reason, he added, is that the voracious bugs ate it.
Now, he said, "since they no longer have the oil, they're eating their [dead] brethren."
The study, published online Tuesday in the journal Science, examined the deep-sea plume of oil 3,600 feet below the surface and up to six miles from the leaking wellhead. The scientists scooped seawater from different points within the plume as well as outside of it.
They assessed the mass of bacteria in their samples several ways: by counting cells under microscopes; measuring how much oxygen was depleted from the water, a sign of active microbial life; and by measuringchemicals called phospholipids (found in bacterial cell membranes).
The researchers also used DNA analysis to identify the types of bacteria they found.
Bacterial populations were low outside the plume, Hazen said, but were 100 times denser in oily areas. Within those prospering colonies, the bacteria that dominated were bugs that had genes for consuming oil.
The DNA of one particular carbon-eater — closely related to a group of bacteria called Oceanospirillales — was found in just 5% of the bugs in a control sample of unpolluted seawater, but more than 90% of the plume-dwelling populations.